Traditional 3D design industries, such as animation design or architectural design, basically only need to consider the shape of the 3D model when designing, and even ignore the physical world. The vast majority of scenes and objects consist only of visible grids, objects are made up of pieces and lines, and do not need to be connected. But if you want to design a 3D model that can be used on a 3D printer and print perfectly as expected, then you need to understand the following:
The 3D model must be watertight
watertight can also be “closed” or “watertight”. Watertight means that the 3D model must be a whole with a complete boundary, if the model leaks, the printer can not identify the boundary, and you can not print. You can check whether your model has such problems with the help of some software.
3D models must be manifold
manifold is a concept in mathematics. You can imagine a surface of flowing water. There are no lines or slices. In simple terms, a 3D model is non-manifold if multiple faces are sharing an edge.
The two cubes share one side, in other words, the side is shared by all four sides. The free software Blender has a feature to determine if a 3D model has non-manifold regions – we can demonstrate this in Blender, as shown below:
Some other 3D software should have similar functions.
1. The maximum size and minimum shell thickness of the 3D model, even the best 3d printer, can not print infinite items, for a large number of designers, especially the art class, who sometimes in the beginning did not consider the print size. For size confirmation, the sooner the better, too large may involve disassembly, too small may lose print details;
The shell is thick, which should be the most common mistake of 3D printing. 3D printing makes objects by layering them on top of each other; If a 3D file has no shell thickness, it is all pieces and lines, and the 3D printer has no way to know how much the layer thickness is, it will not be able to print. For us, there are general requirements for shell thickness, which may be slightly more conservative than the process limit of printing, to reduce the probability of damage during transportation and cleaning;
The maximum size and shell thickness of the 3D model depends on the 3D printing process and the material you want to use. Generally speaking, the thinner shell thickness of the larger size model is not less than 1mm. Otherwise, it is fragile and prone to deformation.
2. The normal direction is consistent
Normal lines are used to distinguish the inner and outer planes, which is important for the printer, otherwise, the 3D printer has no way to recognize the boundaries of the model. The normal direction of all the faces in the 3d model must point in the right direction. If your model contains contradictory normal directions, the 3D printer will not be able to tell whether it is inside or outside the model.
3. Merge overlapping parts
The cross surface will cause the overlapping volume, which will first cause the inaccuracy of the volume calculation, calculate the volume, and also cause problems in the orientation of the positioning surface. Therefore, the cross-coincidence planes must be merged;
4. Minimum gap refers to the minimum distance between the thickness of the two shells, which is still related to the physical limit of the 3D printer, if the minimum gap is less than the printing limit of 3D printing, the two walls will synthesize a result that can not be distinguished or there will be support or residue can not come out. If you want to print a successfully movable item or joint item at one time, there needs to be a 0.6mm gap at the joint or joint to reserve the gap. 7. Other
Printable 3D files should also comply with these rules or recommendations:
1, if you only need to look at the appearance, you can do as much as possible to hollow out, which can save some costs;
2, pay attention to the molding size, if the model is larger than the maximum molding size of the 3D printing equipment, sometimes it is necessary to split printing.
3, the relationship between price and size is close to the third power relationship, so the larger the size, the higher the price, and the growth rate is very fast!
4, the cantilever structure, should make the cantilever structure thicker, to prevent deformation in the printing process.
5. Objects with large radians, such as cylinders, will be less thorough than flat objects if printed using transparent materials.
6, the minimum surface details should not be less than 0.2mm
7, do not have a thin line less than 1.2mm
8. Print items neatly
Designing models for 3D printing is somewhat different from “traditional” 3D design, but it’s not that 3D designers need to re-learn, mainly to understand some new concepts, if you keep these concepts and constraints in mind when designing 3D printing design is not difficult to do.